Header for a heat exchanger

ABSTRACT

A heat exchanger having a first core with a first end and a second end and having a first plurality of hot flow channels fluidly isolated from a first plurality of cool flow channels. The first plurality of hot flow channels and the first plurality of cool flow channels can be arranged in a first checkerboard pattern. The heat exchanger also having a first header connected to the first end of the first core, a first hot flow inlet section connected to the first plurality of hot flow channels, and a first curved portion with a first inner hot flow route that is longer than a first outer hot flow route. The first header also having a first cool flow outlet section connected to the first plurality of cool flow channels with the first cool flow outlet section being fluidly isolated from the hot flow inlet section.

BACKGROUND

The present disclosure relates to heat exchangers and more particularly, to headers for conveying fluid into and out of heat exchangers.

Conventional plate fin heat exchangers are multilayer sandwich layers/cores constructed out of flat sheet metal dividing plates, spacing bars, and two dimensional thin corrugated fins brazed together. The fabrication process is well established and relatively simple. However, the manufacturing simplicity has a negative impact on performance of the heat exchanger (i.e., how well the heat exchanger cools a high-temperature fluid). The integrity of the structure is limited by the strength and quality of the braze joints which may be subject to stress concentration since there is no mechanism to control the size of the corner fillets. Flat geometry of the dividing plates exposed to high pressure causes bending, so thicker plates are used to reduce the stress level, which increase the weight of the heat exchanger. Headers are required to convey hot and cool fluid into and out of the layers of the heat exchangers, but conventional headers add to the pressure drop and may induce large transient thermal stress (due to differences between the heating rate of the headers and the heating rate of the heat exchanger). Further, conventional headers do not increase heat transfer between the hot and the cool fluid. Such conventional systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved heat exchangers and for improved headers for conveying hot and cool fluids to those heat exchangers.

SUMMARY

A heat exchanger includes a first core with a first end and a second end and having a first plurality of hot flow channels fluidly isolated from a first plurality of cool flow channels with the first plurality of hot flow channels and the first plurality of cool flow channels being arranged in a first checkerboard pattern. The heat exchanger also includes a first header connected to the first end of the first core. The first header includes a first hot flow inlet section and a first cool flow outlet section. The first hot inlet section is connected to the first plurality of hot flow channels and has a first curved portion with a first inner hot flow route that is longer than a first outer hot flow route. The first cool flow outlet section is connected to the first plurality of cool flow channels and is fluidly isolated from the hot flow inlet section.

Another embodiment of a heat exchanger includes a core with hot flow channels and cool flow channels with the core having a center and outer edges and a first header connected to a first end of the core. The first header includes a hot flow inlet, first hot flow routes, two cool flow outlets distant from one another, and first cool flow routes. The first hot flow routes connect the hot flow channels to the hot flow inlet, with a first plurality of the first hot flow routes connecting the hot flow channels nearer the outer edges of the core to the hot flow inlet and being longer in length than a second plurality of the first hot flow routes that connect the hot flow channels nearer the center of the core to the hot flow inlet. The first cool flow routes connect the cool flow channels to one of the two cool flow outlets, with a first plurality of the first cool flow routes connecting the cool flow channels nearer the outer edges of the core to one of the two cool flow outlets and being shorter in length than a second plurality of the first cool flow routes that connect the cool flow channels nearer the center of the core to one of the two cool flow outlets.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic of a heat exchanger.

FIG. 1B is a first cross-sectional schematic of the heat exchanger of FIG. 1A taken along line 1B-1B.

FIG. 1C is a second cross-sectional schematic of the heat exchanger of FIG. 1A taken along line 1C-1C.

FIG. 1D is a third cross-sectional schematic of the heat exchanger of FIG. 1A taken along line 1D-1D.

FIG. 1E is a fourth cross-sectional schematic of the heat exchanger of FIG. 1A taken along line 1E-1E.

FIG. 1F is a fifth cross-sectional schematic of the heat exchanger of FIG. 1A taken along line 1F-1F.

FIG. 2A is a perspective view of the heat exchanger.

FIG. 2B is a first cross-sectional perspective view of the heat exchanger.

FIG. 2C is a second cross-sectional perspective view of the heat exchanger.

FIG. 2D is a third cross-sectional perspective view of the heat exchanger.

FIG. 2E is a fourth cross-sectional perspective view of the heat exchanger.

FIG. 2F is a fifth cross-sectional perspective view of the heat exchanger.

FIG. 2G is a sixth cross-sectional perspective view of the heat exchanger.

FIG. 2H is a seventh cross-sectional perspective view of the heat exchanger.

FIG. 2I is an eighth cross-sectional perspective view of the heat exchanger.

FIG. 2J is a ninth cross-sectional perspective view of the heat exchanger.

FIG. 2K is a tenth cross-sectional perspective view of the heat exchanger.

FIG. 2L is an eleventh cross-sectional perspective view of the heat exchanger.

FIG. 3A is a schematic of a heat exchanger pair.

FIG. 3B is a first cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3B-3B.

FIG. 3C is a second cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3C-3C.

FIG. 3D is a third cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3D-3D.

FIG. 3E is a fourth cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3E-3E.

FIG. 3F is a fifth cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3F-3F.

FIG. 4 is a schematic of a heat exchanger system with four heat exchangers.

FIG. 5 is a schematic of another embodiment of a heat exchanger.

DETAILED DESCRIPTION

A heat exchanger with headers is disclosed herein that includes a core, which has a plurality of hot flow channels and a plurality of cool flow channels, and a header, which has either a hot flow inlet section with a cool flow outlet section or a hot flow outlet section with a cool flow inlet section. The heat exchanger can include a second header (opposite the first header) having either a hot flow outlet section with a cool flow inlet section or a hot flow inlet section with a cool flow outlet section. The core of the heat exchanger is configured to promote heat transfer between a hot fluid and a cool fluid by having the plurality of hot flow channels and the plurality of cool flow channels arranged in a checkboard pattern with each of the plurality of hot flow channels being surrounded by some of the plurality of cool flow channels. The plurality of hot flow channels and the plurality of cool flow channels can each have varying cross-sectional flow areas to promote heat transfer. The first header connects the hot flow inlet to the core and the cool flow outlet to the core, and the second header connects the cool flow inlet to the core and hot flow outlet to the core. Each header is arranged in an alternating hot-cool flow path orientation (that transitions the flow from a singular channel inlet or outlet to the checkerboard pattern of the core) so the change in temperature of the headers along a hot/cool flow path is gradual, reducing thermal expansion issues that can be caused by a sudden increase (or decrease) in temperature along a flow path. Further, the headers have a curved portion along each of the hot flow paths and the cool flow paths and the longer inlet flow paths connect to the shorter outlet flow paths such that the total flow path and the pressure drop between each inlet and outlet is nearly equal.

Other embodiments of the heat exchanger can include multiple cores and multiple headers arranged in parallel with one hot flow inlet providing hot fluid to two different headers that each have curved portions (that, in turn, provide hot fluid to two cores), with one cool flow inlet providing cool flow to two different headers that each have curved portions, with one hot flow outlet connected to two different headers that each have curved portions, and with one cool flow outlet connected to two different headers that each have curved portions.

The heat exchanger disclosed herein has numerous benefits. The core having a checkerboard pattern with varying cross-sectional flow areas can be arranged in a counter-flow configuration (i.e., the cool flow is in an opposite direction than the hot flow) that improves heat transfer across the entire length of the core, which increases the heat exchanger effectiveness for a given overall heat transfer area. The counter-flow configuration reduces the temperature differential across the heat exchanger because the cool flow outlet is aligned with the hot flow inlet in the first header (and vice versa in the second header). Further, the checkboard pattern increases the heat transfer surface area in the heat exchanger, which increases the efficiency and limits the need to use fins or other projections into the flow path. The checkerboard pattern enables optimization of high pressure channel shape (e.g., circular instead of rectangular) such that the stress from the pressure of the hot or cool fluid is minimized. The alternating hot-cool flow orientation created by the headers gradually integrates the counter-flow hot and cool routes such that the increase in temperature of the header is gradual, reducing thermal expansion issues and stresses that can result from a sudden increase (or decrease) in temperature along a flow path. The orientation of the curved headers balances out the flow length of each of the hot and cool flow paths so that the pressure drop across the heat exchanger is the same in all flow paths. After reviewing the description and corresponding figures below, these and other benefits will be realized.

FIG. 1A is a schematic of a heat exchanger, FIG. 1B is a first cross-sectional schematic of the heat exchanger taken along line 1B-1B, FIG. 1C is a second cross-sectional schematic of the heat exchanger taken along line 1C-1C, FIG. 1D is a third cross-sectional schematic of the heat exchanger taken along line 1D-1D, FIG. 1E is a fourth cross-sectional schematic of the heat exchanger taken along line 1E-1E, and FIG. 1F is a fifth cross-sectional schematic of the heat exchanger taken along line 1F-1F.

Heat exchanger 20 includes core 22, first header 24, second header 26, hot flow inlet 28, hot flow outlet 30, cool flow inlet 32, and cool flow outlet 34. Core 22 includes first end 40, second end 42, center 44, outer edges 46, a plurality of hot flow channels 48, a plurality of cool flow channels 50, and checkerboard pattern 52. First header 24 includes first hot flow inlet section 60, first curved portion 62, first inner hot flow route 64, first outer hot flow route 66, and first hot flow inlet section layers 68. First header 24 also includes first cool flow outlet section 70, second curved portion 72, first inner cool flow route 74, first outer cool flow route 76, and first cool flow outlet section layers 78. Second header 26 includes first hot flow outlet section 80, third curved portion 82, second inner hot flow route 84, second outer hot flow route 86, and first hot flow outlet section layers 88. Second header 26 also includes first cool flow inlet section 90, fourth curved portion 92, second inner cool flow route 94, second outer cool flow route 96, and first cool flow inlet section layers 98. Between hot flow inlet 28 and hot flow outlet 30 are a plurality of hot flow paths 100, and between cool flow inlet 32 and cool flow outlet 34 are a plurality of cool flow paths 102.

Heat exchanger 20 can be as large or small as necessary, depending on the thermal exchange needs and the environment in which heat exchanger 20 is present (i.e., what type of engine/machine heat exchanger 20 is a part of, such as a gas turbine engine, electronics, etc.). Further, heat exchanger 20 can be configured to transfer as much or as little thermal energy as desired. While heat exchanger 20 is described as utilizing hot and cool fluid flowing through the plurality of hot flow paths 100 (the entire flow paths between hot flow inlet 28 and hot flow outlet 30) and the plurality of cool flow paths 102 (the entire flow paths between cool flow inlet 32 and cool flow outlet 34), respectively, the fluids can be air, another type of gas, or a liquid, such as cooling lubricant or water. Also, while heat exchanger 20 is described with regards to two different flow paths (the plurality of hot flow paths 100 between hot flow inlet 28 and hot flow outlet 30 and the plurality of cool flow paths 102 between cool flow inlet 32 and cool flow outlet 34), the temperature of the fluid flowing through heat exchanger 20 is arbitrary in that the temperature of the fluid flowing through heat exchanger 20 can be any temperature. For example, the fluid flowing into hot flow inlet 28 can be at a cooler temperature than the fluid flowing into cool flow inlet 32.

As described below, multiple heat exchangers 20 can be utilized in parallel, and multiple heat exchangers 20 can be incorporated into one another such that hot flow inlet 28, hot flow outlet 30, cool flow inlet 32, and cool flow outlet 34 provide hot and cool flow to multiple heat exchangers 20. Heat exchanger 20 can be one continuous and monolithic piece, or each component of heat exchanger 20 can be multiple pieces fastened to one another. Heat exchanger 20 can be formed through a variety of manufacturing processes, such as forming pieces separately and fastening those pieces together or constructing all or parts of heat exchanger 20 through additive manufacturing. Heat exchanger 20 can be constructed from a variety of materials, including plastic, metal, an alloy, or another material. However, constructing heat exchanger 20 from a thermally conductive material may be beneficial to promote the transfer of thermal energy from the hot fluid to the cool fluid. In one embodiment, the disclosed heat exchanger 20 is constructed from a nickel-based alloy.

Core 22 of heat exchanger 20 has checkerboard pattern 52 made up of the plurality of hot flow channels 48 and the plurality of cool flow channels 50. Core 22 can be any size and shape, but core 22 in the disclosure is approximately a rectangular cuboid between first end 40 and second end 42. Core 22 has outer edges 46 and center 44 (shown in FIG. 1C), with outer edges 46 being outer walls when viewed perpendicular to the plurality of hot flow channels 48 and the plurality of cool flow channels 50 and center 44 being at an internal location when viewed perpendicular to the plurality of hot flow channels 48 and the plurality of cool flow channels 50. The hot flow channels near center 44 are adjacent cool flow channels, while the hot flow channels near outer edges 46 are along outer walls and are only adjacent cool flow channels on two sides (when near a corner) or three sides. Core 22 is the primary thermal exchange portion of heat exchanger 20, and the plurality of hot flow channels 48 and the plurality of cool flow channels 50 can have any configuration in relation to each other. Though, as shown in FIG. 1D, each of the plurality of hot flow channels 48 is adjacent to and surrounded by some of the plurality of cool flow channels 50 (i.e., alternating hot-cool flow channels) with the flow of hot and cool fluid going in an opposite direction. For example, hot fluid flowing through the plurality of hot flow channels 48 flows from first end 40 to second end 42, while cool fluid flowing through the plurality of cool flow channels 50 flows from second end 42 to first end 40. Further, the plurality of hot flow channels 48 and the plurality of cool flow channels 50 within core 22 can be configured such that some of the plurality of cool flow channels 50 are along outer edges 46, as shown in FIG. 2L, with the plurality of hot flow channels 48 being closer to center 44.

The plurality of hot flow channels 48 and the plurality of cool flow channels 50 can have a constant and unvaried cross-sectional shape/configuration throughout the length of core 22 between first end 40 and second end 42. Alternatively, the cross-sectional shape/configuration can be varied, such as a change in the shape of each flow channel (e.g., a flow channel transitioning from a rectangular cross section to a circular cross section), the merging of flow channels (e.g., two flow channels of the plurality of hot flow channels 48 merge to create one flow channel), or another configuration. As shown in FIGS. 2A-2L, the cross sections of each flow channel of the plurality of hot flow channels 48 and the plurality of cool flow channels 50 of core 22 can vary to transition the plurality of hot flow channels 48 and the plurality of cool flow channels 50 through core 22 from layers at first end 40 connected to first header 24 and at second end 42 connected to second header 26 to checkerboard pattern 52 near a middle of core 22. The configuration of core 22 can be designed depending on the thermal exchange needs of heat exchanger 20 and the apparatus in which heat exchanger 20 is utilized.

Core 22 can be one continuous and monolithic piece, or core 22 can be multiple pieces fastened together, such as each of the plurality of hot flow channels 48 and the plurality of cool flow channels 50 being formed separately and fastened to one another to create checkerboard pattern 52. Further, core 22 can be integrated into heat exchanger 20 such that heat exchanger 20 is one continuous and monolithic piece. Additive manufacturing may be used to minimize manufacturing tolerances and to ensure walls forming the plurality of hot flow channels 48 and the plurality of cool flow channels 50 are relatively thin, promoting heat transfer. Core 22 can be constructed from the same material as that used in the other components of heat exchanger 20, or core 22 can be constructed from another material, such as those materials discussed above.

First header 24 is connected to first end 40 of core 22 at one end and to hot flow inlet 28 and cool flow outlet 34 at another end. First hot flow inlet section 60 extends between hot flow inlet 28 and the plurality of hot flow channels 48 of core 22 (to form a portion of the plurality of hot flow paths 100 shown in FIG. 1A), and first cool flow outlet section 70 extends between the plurality of cool flow channels 50 and cool flow outlet 34 (to form a portion of the plurality of cool flow paths 102 shown in FIG. 1A). First header 24 can be one continuous and monolithic piece, or first header 24 can be multiple pieces fastened together, such as first hot flow inlet section 60 and first cool flow outlet section 70 being formed separately and fastened together during the manufacturing process. Further, first header 24 can be integrated into heat exchanger 20 such that heat exchanger 20 is one continuous and monolithic piece. All or part of first header 24 can be constructed using additive manufacturing.

First hot flow inlet section 60 is integrated with first cool flow outlet section 70 such that flow routes of each section alternate with each other (i.e., a hot flow route is adjacent to a cool flow route). As shown in FIGS. 1B and 1C, the flow routes in first hot flow inlet section 60 transition from an open, hot flow inlet 28 to first hot flow inlet section layers 68 (that alternate with first cool flow outlet section layers 78), and then to the plurality of hot flow channels 48 that make up checkerboard pattern 52 of core 22. Similarly, the flow routes in first cool flow outlet section 70 transition from the plurality of cool flow channels 50 that make up checkerboard pattern 52 of core 22 to first cool flow outlet section layers 78 (that alternate with first hot flow inlet section layers 68), and then to an open, cool flow outlet 34. While hot flow inlet 28 and cool flow outlet 34 can be positioned anywhere adjacent to first header 24, FIGS. 1A-1F show hot flow inlet 28 and cool flow outlet 34 on opposite sides of first header 24. With such a configuration, multiple heat exchangers 20 can be configured in parallel with adjacent heat exchangers 20 sharing a hot flow inlet 28 and a cool flow outlet 34 (as will be discussed with regards to FIGS. 3A-3F and 4).

First hot flow inlet section 60 includes first curved portion 62 that directs hot fluid from hot flow inlet 28 to core 22. First curved portion 62 is divided into flow routes, with first inner hot flow route 64 being a hot flow route that has the greatest curve (the longest flow route between hot flow inlet 28 and core 22) and first outer hot flow route 66 being a hot flow route that does not have a curve or has only a mild curve (the shortest flow route between hot flow inlet 28 and core 22). Between first inner hot flow route 64 and first outer hot flow route 66 are other flow routes having lengths that are between a length of the first inner hot flow route 64 and a length of the first outer hot flow route 66. All of the flow routes through first curved portion 62 of first hot flow inlet section 60 convey hot fluid from hot flow inlet 28 to core 22. First inner hot flow route 64 is nearest a side opposite hot flow inlet 28, while first outer hot flow route 66 is the flow route of first curved portion 62 closest to a side nearest hot flow inlet 28. Along the flow route, first inner hot flow route 64 transitions from the open, hot flow inlet 28 (FIG. 1B) to separate layers making up first hot flow inlet section layers 68 (FIG. 1C), then to some of the plurality of hot flow channels 48 closest the side opposite hot flow inlet 28 (FIG. 1D). Similarly, along the flow route, first outer hot flow route 66 transitions from the open, hot flow inlet 28 (FIG. 1B) to separate layers making up first hot flow inlet section layers 68 (FIG. 1C), then to some of the plurality of hot flow channels 48 closest to the side nearest hot flow inlet 28 (different flow channels than those which first inner hot flow route 64 transitions to) (FIG. 1D). The flow routes between first inner hot flow route 64 and first outer hot flow route 66 make a similar transition, culminating in the plurality of hot flow channels 48 between the two sides of core 22.

First curved portion 62 results in a varied length of the flow routes between hot flow inlet 28 and core 22. However, as will be described below, the flow routes of third curved portion 82 of first hot flow outlet section 80 of second header 26 also have a varied length, but those lengths balance out the varied lengths of the flow routes of first curved portion 62 such that all of the plurality of hot flow paths 100 are approximately equal in length. The balancing out of the lengths of each of the plurality of hot flow paths 100 is accomplished by third curved portion 82 having flow routes that are the inverse of those in first curved portion 62 (i.e., hot fluid that flows through the longer first outer hot flow route 66 of first curved portion 62 will then flow through the shorter second inner hot flow route 84 (after flowing through core 22), and hot fluid that flows through the shorter first inner hot flow route 64 will then flow through the longer second outer hot flow route 86 (after flowing through core 22)).

First cool flow outlet section 70 has a very similar configuration to first hot flow inlet section 60, except that first cool flow outlet section 70 is mirrored to first hot flow inlet section 60 (i.e., because cool flow outlet 34 (to which first cool flow outlet section 70 is connected) is on an opposite side from hot flow inlet 28). First cool flow outlet section 70 is integrated with first hot flow inlet section 60 such that flow routes of each section alternate with each other (i.e., a cool flow route is adjacent to a hot flow route).

First cool flow outlet section 70 includes second curved portion 72 that directs cool fluid from core 22 to cool flow outlet 34. Second curved portion 72 has a similar configuration to first curved portion 62 of first hot flow inlet section 60, except that second curved portion 72 is mirrored to first curved portion 62. Second curved portion 72 is divided into flow routes, with first inner cool flow route 74 being a cool flow route that has the greatest curve (the longest flow route between core 22 and cool flow outlet 34) and first outer cool flow route 76 being a cool flow route that does not have a curve or has a mild curve (the shortest flow route between core 22 and cool flow outlet 34). Between first inner cool flow route 74 and first outer cool flow route 76 are flow routes having lengths that are between a length of the first inner cool flow route 74 and a length of the first outer cool flow route 76. All of the flow routes through second curved portion 72 of first cool flow outlet section 70 convey cool fluid from core 22 to cool flow outlet 34 because cool fluid in first header 24 flows in an opposite direction than hot fluid. First inner cool flow route 74 is nearest a side opposite cool flow outlet 34, while first outer cool flow route 76 is the flow route of second curved portion 72 closest to a side nearest cool flow outlet 34. Along the flow route, first inner cool flow route 74 transitions some of the plurality of cool flow channels 50 closest the side opposite cool flow outlet 34 (FIG. 1D) to separate layers making up first cool flow outlet section layers 78 (FIG. 1C), then to the open, cool flow outlet 34 (FIG. 1B). Similarly, along the flow route, first outer cool flow route 76 transitions from some of the plurality of cool flow channels 50 closest to the side nearest cool flow outlet 34 (different flow channels than those which first inner cool flow route 74 transitioned from) (FIG. 1C) to separate layers making up first cool flow outlet section layers 78 (FIG. 1B), then to the open, cool flow outlet 34 (FIG. 1B). The flow routes between first inner cool flow route 74 and first outer cool flow route 76 make a similar transition from the plurality of cool flow channels 50 between the two ends of core 22 to cool flow outlet 34.

Similarly to first curved portion 62 of first hot flow inlet section 60, second curved portion 72 of first cool flow outlet section 70 results in a varied length of the flow routes between core 22 and cool flow outlet 34. However, the flow routes of fourth curved portion 92 of first cool flow inlet section 90 of second header 26 also have a varied length, but those lengths balance out the varied lengths of the flow routes of second curved portion 72 such that all of the plurality of cool flow paths 102 are approximately equal in length. The balancing out of the lengths of each of the plurality of cool flow paths 102 is accomplished by fourth curved portion 92 having flow routes that are the inverse of those in second curved portion 72 (i.e., cool fluid that flows through the shorter first outer cool flow route 76 of second curved portion 72 will have previously flowed through the longer second inner cool flow route 94 (after flowing through core 22), and cool fluid that flows through the longer first inner cool flow route 74 will have previously flowed through the shorter second outer cool flow route 96 (after flowing through core 22)).

For at least a portion of first header 24, first hot flow inlet section layers 68 are alternating with first cool flow outlet section layers 78 (FIG. 1C) between core 22 and hot flow inlet 28 and cool flow outlet 34 to provide a gradual heat transfer zone. The alternating hot-cool layers create a decrease in temperature of hot fluid within first hot flow inlet section 60 and the increase in temperature of cool fluid within first cool flow outlet section 70 that is gradual, reducing thermal expansion issues and stresses within first header 24 that can result from a sudden increase or decrease in temperature along the flow paths (which could be present between a nonintegrated header and core 22). Further, first hot flow inlet section layers 68 and first cool flow outlet section layers 78 provide a smooth transition from hot flow inlet 28 and core 22 and core 22 and cool flow outlet 34, respectively, so that the pressure drop across heat exchanger 20 is reduced.

Second header 26 has the same configuration as first header 24, except that the flow of hot fluid is out of core 22 to hot flow outlet 30 and the flow of cool fluid is into core 22 from cool flow inlet 32. Second header 26 is connected to second end 42 of core 22 at one end and to hot flow outlet 30 and cool flow inlet 32 at another end. First hot flow outlet section 80 extends between the plurality of hot flow channels 48 of core 22 and hot flow outlet 30 (forming a portion of the plurality of hot flow paths 100), and first cool flow inlet section 90 extends between cool flow outlet 34 and the plurality of cool flow channels 50 (forming a portion of the plurality of cool flow paths 102). Second header 26 can be one continuous and monolithic piece, or second header 26 can be multiple pieces fastened together, such as first hot flow outlet section 80 and first cool flow inlet section 90 being formed separately and fastened together during the manufacturing process. Further, second header 26 can be integrated into heat exchanger 20 such that heat exchanger 20 is one continuous and monolithic piece. All or part of second header 26 can be constructed using additive manufacturing.

First hot flow outlet section 80 is similar in configuration to first hot flow inlet section 60, with first hot flow outlet section 80 conveying hot fluid (which is cooler than when the hot fluid is flowing through first hot flow inlet section 60) from the plurality of hot flow channels 48 of core 22 to hot flow outlet 30. First hot flow outlet section 80 is integrated with first cool flow inlet section 90 such that flow routes of each section alternate with each other (i.e., a hot flow route is adjacent to a cool flow route). As shown in FIGS. 1D, 1E, and 1F, the flow routes in first hot flow outlet section 80 transition from the plurality of hot flow channels 48 that make up checkerboard pattern 52 of core 22 (FIG. 1D) to first hot flow outlet section layers 88 (that alternate with first cool flow inlet section layers 98) (FIG. 1E), and then to an open, hot flow outlet 30 (FIG. 1F). Similarly, the flow routes in first cool flow inlet section 90 transition from an open, cool flow outlet 34 (FIG. 1F) to first cool flow inlet section layers 98 (that alternate with first hot flow outlet section layers 88) (FIG. 1E), and then to the plurality of cool flow channels 50 that make up checkerboard pattern 52 of core 22 (FIG. 1D). While cool flow inlet 32 and hot flow outlet 30 can be positioned anywhere adjacent to second header 26, FIGS. 1A-1F show cool flow inlet 32 on an opposite side of second header 26 than hot flow inlet 30. With such a configuration, multiple heat exchangers 20 can be configured in parallel with adjacent heat exchangers 20 sharing a hot flow outlet 32 and a cool flow inlet 32 (as will be discussed with regards to FIGS. 3A-3F and 4).

First hot flow outlet section 80 includes third curved portion 82 divided into flow routes (that correspond to the flow routes of first curved portion 62), with second inner hot flow route 84 being a hot flow route that has the greatest curve (the longest flow route between core 22 and hot flow outlet 30) and second outer hot flow route 86 being a hot flow route that does not have a curve or has a mild curve (the shortest flow route between core 22 and hot flow outlet 30). Between second inner hot flow route 84 and second outer hot flow route 86 are other flow routes having lengths that are between a length of the second inner hot flow route 84 and a length of the second outer hot flow route 86. All of the flow routes through third curved portion 82 of first hot flow outlet section 80 convey hot fluid from core 22 to hot flow outlet 30.

As mentioned previously, first hot flow outlet section 80 and third curve portion 82 have a configuration similar to first hot flow inlet section 60 and first curved portion 62, including the configuration of second inner hot flow route 84 (similar to first inner hot flow route 64), second outer hot flow route 86 (similar to first outer hot flow route 86), and first hot flow outlet section layers 88 (similar to first hot flow inlet section layers 68). However, hot flow outlet 30 of second header 26 is located on the opposite side from hot flow inlet 28 of first header 24, so second inner hot flow route 84 corresponds to first outer hot flow route 66 (i.e., fluid flowing through one will flow through the other) and second outer hot flow route 86 corresponds to first inner hot flow route 64 (i.e., fluid flowing through one will flow through the other). Thus, first outer hot flow route 66 is along the same flow path of the plurality of hot flow paths 100 as second inner hot flow route 84, and first inner hot flow route 64 is along the same flow path of the plurality of hot flow paths 100 as second outer hot flow route 86 (but a different flow path than first outer hot flow route 66 and second inner hot flow route 84). A similar configuration is present for those flow paths therebetween (e.g., a flow route in first hot flow inlet section 60 closer to first outer hot flow route 66 will correspond to a flow route in first hot flow outlet section 80 closer to second inner hot flow route 84, and similarly for other flow paths). With such a configuration, each flow path of the plurality of hot flow paths 100 will have an approximately equal length between hot flow inlet 28 and hot flow outlet 30. The curved orientation of first curved portion 62 and third curved portion 82 balance out the length of each flow path of the plurality of hot flow paths 100 so that that the pressure drop across each of the plurality of hot flow paths 100 is approximately equal.

First cool flow inlet section 90 is similar in configuration to first cool flow outlet section 70, with first cool flow inlet section 90 conveying cool fluid (which is cooler than when the cool fluid is flowing through first cool flow outlet section 70) from cool flow inlet 32 to the plurality of cool flow channels 50 of core 22. As shown in FIGS. 1D, 1E, and 1F, the flow routes in first cool flow inlet section 90 transition from an open, cool flow inlet 32 (FIG. 1F) to first cool flow inlet section layers 98 (that alternate with first hot flow outlet section layers 88) (FIG. 1E), and then to the plurality of cool flow channels 50 that make up checkerboard pattern 52 of core 22 (FIG. 1D).

First cool flow inlet section 90 includes fourth curved portion 92 divided into flow routes (that correspond to the flow routes of second curved portion 72), with second inner cool flow route 94 being a cool flow route that has the greatest curve (the longest flow route between cool flow inlet 32 and core 22) and second outer cool flow route 96 being a cool flow route that does not have a curve or has a mild curve (the shortest flow route between cool flow inlet 32 and core 22). Between second inner cool flow route 94 and second outer cool flow route 96 are other flow routes having lengths that are between a length of the second inner cool flow route 94 and a length of the second outer cool flow route 96. All of the flow routes through fourth curved portion 92 of first cool flow inlet section 90 convey cool fluid from cool flow inlet 32 to core 22.

As mentioned previously, first cool flow inlet section 80 and fourth curve portion 92 have a configuration similar to first cool flow outlet section 70 and second curved portion 72, including the configuration of second inner cool flow route 94 (similar to first inner cool flow route 74), second outer cool flow route 96 (similar to first outer cool flow route 76), and first cool flow inlet section layers 98 (similar to first cool flow outlet section layers 78). However, cool flow inlet 32 of second header 26 is located on the opposite side from cool flow outlet 34 of first header 26, so second inner cool flow route 94 corresponds to first outer cool flow route 76 (i.e., fluid flowing through one will flow through the other) and second outer cool flow route 96 corresponds to first inner cool flow route 74 (i.e., fluid flowing through one will flow through the other). Thus, first outer cool flow route 76 is along the same flow path of the plurality of cool flow paths 102 as second inner cool flow route 94, and first inner cool flow route 74 is along the same flow path of the plurality of cool flow paths 102 as second outer cool flow route 96 (but a different flow path than first outer cool flow route 76 and second inner cool flow route 94). A similar configuration is present for those flow paths therebetween (e.g., a flow route in first cool flow outlet section 70 closer to first outer cool flow route 76 will correspond to a flow route in first cool flow inlet section 90 closer to second inner cool flow route 94, and similarly for other flow paths). With such a configuration, each flow path of the plurality of cool flow paths 102 will have an approximately equal length between cool flow inlet 32 and cool flow outlet 34. The curved orientation of second curved portion 72 and fourth curved portion 92 balance out the length of each flow path of the plurality of cool flow paths 102 so that that the pressure drop across each of the plurality of cool flow paths 102 is approximately equal, minimizing thermal energy transfer issues and increasing the predictability of heat exchanger 20. Depending on the configuration of heat exchanger 20 and design considerations, the plurality of hot flow paths 100 can have an approximately equal length as the plurality of cool flow paths 102, or the plurality of hot flow paths 100 can be shorter or longer than the plurality of cool flow paths 102.

Core 22, first header 24, and second header 26 of heat exchanger 20 work together to promote thermal energy transfer between the hot fluid and the cool fluid by conveying hot fluid between hot flow inlet 28 and hot flow outlet 30 and cool fluid between cool flow inlet 32 and cool flow outlet 34. The curved orientation of the plurality of hot flow paths 100 and the plurality of cool flow paths 102 through heat exchanger 20 provides numerous benefits. Each of the plurality of hot flow paths 100 have a length that is approximately equal, resulting in a similar pressure drop across all flow paths of the plurality of hot flow paths 100. Similarly, each of the plurality of cool flow paths 102 have a length that is approximately equal, resulting in a similar pressure drop across all flow paths of the plurality of cool flow paths 100. Further, the curved and alternating flow configuration (i.e., the flow of cool fluid through the plurality of cool flow paths 102 is in an opposite direction to the flow of hot fluid through the plurality of hot flow paths 100) gradually integrate the plurality of hot flow paths 100 and the plurality of cool flow paths 102 such that the increase in temperature in first header 24 and second header 26 is gradual, reducing thermal expansion issues and stresses that could result throughout heat exchanger 20.

For some applications heat exchanger 20 would be installed entirely within a cool flow duct or flow stream. In that case, first header 24 and second header 26 can be configured such that first cool flow outlet section 70 and first cool flow inlet section 90 do not have second curved portion 72 and fourth curved portion 92, respectively, such that the flow of cooling fluid through heat exchanger 20 is relatively straight with no curves (as will be described in greater detail in FIG. 5). When heat exchanger 20 has relatively straight cool flow paths of the plurality of cool flow paths 102, first header 24 could still include first curved portion 62 and second header 26 could still include third curved portion 82.

FIG. 2A-2L is a series of cross-sectional perspective views of heat exchanger 20 showing the transition of the plurality of hot flow paths 100 and the plurality of cool flow paths 102 from hot flow inlet 28 and cool flow outlet 34, respectively, to core 22.

FIG. 2A is a perspective view of heat exchanger 20. As described above with regards to the schematic of heat exchanger 20, heat exchanger 20 includes core 22 between first header 24 and second header 26, with first header 24 connected to hot flow inlet 28 and cool flow outlet 34, and second header 26 connected to hot flow outlet 30 and cool flow inlet 32. First header 24 includes first hot flow inlet section 60 with first curved portion 62 (not shown) and first cool flow outlet section 70 with second curved portion 72 (not shown). Second header 26 includes first hot flow outlet section 80 with third curved portion 82 (not shown) and first cool flow inlet section 90 with second curved portion 92 (not shown). Hot flow inlet 28 in FIG. 2A is a circular opening that is not yet divided into multiple flow paths of the plurality of hot flow paths 100. Similarly, cool flow outlet 34 in FIG. 2A is a circular opening where the plurality of cool flow paths 102 have converged to form one circular flow path. While heat exchanger 20 of FIG. 2A-2L shows hot flow inlet 28 and hot flow outlet 30 having a smaller diameter than cool flow inlet 32 and cool flow outlet 34, the inlets and outlets can have other sizes and shapes, such as inlets that are larger or smaller than the outlets, inlets and outlets that are noncircular, or other configurations.

FIG. 2B is a first cross-sectional perspective view of heat exchanger 20 showing first cold flow outlet section 70 divided into a number of discrete vertical flow routes. First inner cool flow route 74 is on a side closest to hot flow inlet 28, while first outer cool flow route 76 is on another side distant from hot flow inlet 28. Between first inner cool flow route 74 and first outer cool flow route 76 are other cool flow routes. While FIGS. 2A-2L show the flow routes of first hot flow inlet section 60 and first cool flow outlet section 70 being divided by walls into separate and discrete paths (e.g., first cool flow outlet section 70 is shown with four flow routes in FIG. 2B, first hot flow inlet section 60 is shown with three flow routes in FIG. 2C, etc.), the flow routes of hot flow inlet section 60 and the flow routes of cool flow outlet section 70 do not need to be divided into discrete flow routes by walls. Rather, the flow routes can be connected across the cross section (i.e., no walls between flow routes) and only become discrete flow paths when each flow route transitions to checkerboard pattern 52. For example, the flow routes of first hot flow inlet section 60 can be connected to one another until the cross section shown in FIG. 2J when each of the plurality of hot flow channels 48 become separated by adjacent flow channels of the plurality of cool flow channels 50. Similarly, the flow routes of first cool flow outlet 70 do not need to be divided into discrete flow routes by walls and can be connected across the cross section (i.e., no walls between flow routes).

FIG. 2C is a second cross-sectional perspective view of heat exchanger 20 showing first hot flow inlet section 60 divided into a number of flow routes. First inner hot flow route 64 is on a side closest to cool flow outlet 34, while first outer hot flow route 66 is on another side distant from cool flow outlet 34. Between first inner hot flow route 64 and first outer cool flow route 66 are other cool flow routes. The schematic of FIG. 1 shows first outer hot flow path 66 and first outer cool flow path 76 as uncurved (i.e., a straight flow path) between hot flow inlet 28 and core 22 and between cool flow outlet 34 and core 22, but, as shown in FIGS. 2A-2L, first outer hot flow path 66 and first outer cool flow path 76 can have a slight curve due to hot flow inlet 28 being horizontally offset from core 22 and cool flow outlet 34 being offset from core 22. A similar configuration can be present with hot flow outlet 30, cool flow inlet 32, and header 26. While first outer hot flow route 66 and first outer cool flow route 76 may have a curve that makes each flow route slightly longer, each flow path of the plurality of hot flow paths 100 and each flow path of the plurality of cool flow paths 102 through heat exchanger 20 will still have approximately the same length as other hot or cool flow paths because second outer hot flow route 86 and second outer cool flow route 96 will also have a slight curve to balance out the lengths of each flow path of the plurality of hot flow paths 100 and each flow path of the plurality of cool flow paths 102. Heat exchanger 20 can have other configurations, such as a configuration in which hot flow inlet 28 and hot flow outlet 30 are in another horizontal and/or vertical position in relation to core 22, cool flow inlet 32 and cool flow outlet 34 are in another horizontal and/or vertical position in relation to core 22, or another configuration.

FIG. 2D is a third cross-sectional perspective view of heat exchanger 20 showing first inner hot flow route 64 and first inner cool flow route 74 beginning to divide into separate layers. First inner hot flow route 64 has a longer flow path than that of first outer hot flow route 66 because first inner hot flow route 64 must connect hot flow inlet 28 on one side to a portion of the plurality of hot flow channels 48 of core 22 that are located on a side of heat exchanger 20 opposite hot flow inlet 28. Therefore, first inner hot flow route 64 must extend further across first header 24 than first outer hot flow route 66, which connects hot flow inlet 28 to a portion of the plurality of hot flow channels 48 of core 22 that are located on the same side of heat exchanger 20 as hot flow inlet 28. Similarly, first inner cool flow route 74 has a longer flow path than that of first outer cool flow route 76 because first inner cool flow route 74 must connect a portion of the plurality of cool flow channels 50 of core 22 that are located on a side of heat exchanger 20 opposite cool flow outlet 34 to cool flow outlet 34. Therefore, first inner cool flow route 74 must extend further across first header 24 than first outer cool flow route 66, which connect a portion of the plurality of cool flow channels 50 of core 22 that are located on the same side of heat exchanger 20 as cool flow outlet 34 to cool flow outlet 34.

FIG. 2E is a fourth cross-sectional perspective view of heat exchanger 20 showing first inner hot flow route 64 and first inner cool flow route 74 beginning to divide into first hot flow inlet section layers 68 and first cool flow outlet section layers 78, respectively.

FIG. 2F is a fifth cross-sectional perspective view of heat exchanger 20 showing the hot flow routes and the cool flow routes transitioning into first hot flow inlet section layers 68 and first cool flow outlet section layers 78, respectively, in an alternating layer configuration. The alternating layer configuration of first hot flow inlet section 60 and first cool flow outlet section 70 of first header 24 has first cool flow outlet section layers 78 both on a top and a bottom with first hot flow inlet section layers 68 alternating with first cool flow outlet section layers 78 in a middle. Heat exchanger 20 can have other configurations of first hot flow inlet section layers 68 and first cool flow outlet section layers 78, such as a configuration in which first hot flow inlet section layers 68 are on the top, on the bottom, or both the top and the bottom (i.e., the inverse of what is shown in FIG. 2F-2L) with first cool flow outlet section layers 78 alternating with first hot flow inlet section layers 68 in the middle.

FIG. 2G is a sixth cross-sectional perspective view of heat exchanger 20 showing further developed first hot flow inlet section layers 68 and first cool flow outlet section layers 78. With the gradual integration of first hot flow inlet section 60 and first cool flow outlet section 70 as shown in FIGS. 2E-2G, the thermal energy transfer between the hot fluid flowing through first hot flow inlet section 60 and the cool fluid flowing through first cool flow outlet section 70 is gradual to reduce thermal expansion issues and stresses that result if such a gradual transition is not present.

FIG. 2H is a seventh cross-sectional perspective view of heat exchanger 20 showing fully developed first hot flow inlet section layers 68 and first cool flow outlet section layers 78 at a transition point where first header 24 connects to first end 40 of core 22. At this point, first hot flow inlet section layers 68 span across a total horizontal length of first header 24 and have a vertical height that is constant along the total horizontal length. Similarly, first cool flow outlet section layers 78 span across the total horizontal length of first header 24 and have a vertical height that is constant along the total horizontal length. While the hot flow routes and cool flow routes have only transitioned to first hot flow inlet section layers 68 and first cool flow outlet section layers 78 at the point where first header 24 connected to core 22 (as opposed to transitioning to checkerboard pattern 52), first header 24 can be configured such that first header 24 transitions from layers to a fully developed checkerboard pattern 52 (as shown in FIG. 2I-2L) entirely within first header 24 instead of partially within core 22. Further, if desired, core 22 can include only layers instead of transitioning into checkerboard pattern 52, or core 22 can have another configuration.

FIG. 2I is an eighth cross-sectional perspective view of heat exchanger 20 showing first hot flow inlet section layers 68 beginning to transition from layers having a constant vertical height to discrete flow channels of the plurality of hot flow channels 48. Such a transition may cause each flow channel of the plurality of hot flow channels 48 and each flow channel of the plurality of cool flow channels 50 to increase or decrease in cross-sectional area, depending on design and/or other considerations.

FIG. 2J is a ninth cross-sectional perspective view of heat exchanger 20 showing the plurality of hot flow paths 100 that are almost transitioned to discrete flow channels of the plurality of hot flow channels 48 within core 22. At this point, each of the plurality of hot flow channels 48 are adjacent to two hot flow channels of the plurality of hot flow channels 48 and two four cool flow channels of the plurality of cool flow channels 50 of core 22. The plurality of hot flow channels 48 form an argyle pattern with each of the plurality of hot flow channels 48 having an approximately stretched-diamond (i.e., lozenge) shape. Cool flow channels of the plurality of cool flow channels 50 that are closer to center 44 of core 22 can have a hexagonal shape, while the cool flow channels of the plurality of cool flow channels 50 near outer edge 46 can have a variety of shapes, but may have a shape that ensures core 22 has an approximately rectangular cross section.

FIG. 2K is a tenth cross-sectional perspective view of heat exchanger 20 showing the plurality of hot flow channels 48 of core 22 transitioning such that each has a diamond shape surrounded by the plurality of cool flow channels 50, with some of the plurality of cool flow channels 50 near center 44 having an octagonal or hexagonal shape.

FIG. 2L is an eleventh cross-sectional perspective view of heat exchanger 20 showing a fully developed checkerboard pattern 52 of core 22 with the plurality of hot flow channels 48 having a quasi-circular/square shape and the plurality of cool flow channels 50 surrounding the plurality of hot flow channels 50. While FIG. 2L shows core 22 with a rectangular cross section, core 22 can have another configuration, such as a circular cross section, a square cross section, an oval cross section, or another shaped cross section. Further, while a portion of the plurality of cool flow channels 50 are on outer edges 46 with no plurality of hot flow channels 48 along outer edges 46, core 22 can be configured so that some or all of the flow channels along outer edges 46 are hot flow channels.

While FIGS. 2A-2L show cross sections at various points along first header 24 and core 22, cross sections at various points along second header 26 and core 22 would be similar with the plurality of hot flow paths 100 transitioning from the plurality of hot flow channels 48 of core 22 to first hot flow outlet section layers 88 of first hot outlet section 80, and then to hot flow outlet 30, and the plurality of cool flow paths 102 transitioning from cool flow inlet 32 to first cool flow inlet section layers 98 of first cool flow inlet section 90, and then to the plurality of cool flow channels 50 of core 22. Additionally, while heat exchanger 20 in FIGS. 2A-2L is shown as only one heat exchanger 20, multiple heat exchangers can be arranged in parallel such that the cores of each of the multiple heat exchangers are adjacent to one another and adjacent heat exchangers share one hot flow inlet (i.e., one hot flow inlet provides hot fluid to two first headers), one hot flow outlet (i.e., two second headers convey hot fluid from two cores to one hot flow outlet), one cool flow inlet (i.e., one cool flow inlet provides cool fluid to two second headers), and one cool flow outlet (i.e., two first headers convey cool fluid from two cores to one cool flow outlet). A configuration including two heat exchangers in parallel is described with regards to FIGS. 3A, 3B, 3C, 3D, 3E, and 3F, and a configuration including four heat exchangers in parallel is described with regards to FIG. 4.

FIG. 3A is a schematic of a heat exchanger pair, FIG. 3B is a first cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3B-3B, FIG. 3C is a second cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3C-3C, FIG. 3D is a third cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3D-3D, FIG. 3E is a fourth cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3E-3E, and FIG. 3F is a fifth cross-sectional schematic of the heat exchanger pair of FIG. 3A taken along line 3F-3F.

Heat exchanger pair 110 includes heat exchanger 20 (as discussed with regards to FIGS. 1A-1F and FIGS. 2A-2L) and heat exchanger 120. Heat exchanger 20 has the same configuration and includes the same components as those discussed in the previous paragraphs. Similar to heat exchanger 20, heat exchanger 120 includes core 122, third header 124, fourth header 126, second hot flow inlet 128, and second cool flow inlet 132. Heat exchanger 120 shares hot flow outlet 30 and cool flow outlet 34 with heat exchanger 20 such that first header 24 and third header 124 both connect to cool flow outlet 34, and second header 26 and fourth header 126 both connect to hot flow outlet 30. Core 122 includes first end 140, second end 142, center 144, outer edges 146, a plurality of hot flow channels 148, a plurality of cool flow channels 150, and checkerboard pattern 152. Third header 124 includes second hot flow inlet section 160, fifth curved portion 162, third inner hot flow route 164, third outer hot flow route 166, and second hot flow inlet section layers 168. Third header 124 also includes second cool flow outlet section 170, sixth curved portion 172, third inner cool flow route 174, third outer cool flow route 176, and second cool flow outlet section layers 178. Fourth header 126 includes second hot flow outlet section 180, seventh curved portion 182, fourth inner hot flow route 184, fourth outer hot flow route 186, and second hot flow outlet section layers 188. Fourth header 126 also includes second cool flow inlet section 190, eighth curved portion 192, fourth inner cool flow route 194, fourth outer cool flow route 196, and second cool flow inlet section layers 198. Between second hot flow inlet 128 and hot flow outlet 30 are a second plurality of hot flow paths 200, and between second cool flow inlet 132 and cool flow outlet 34 are a second plurality of cool flow paths 202.

The configuration and functionality of heat exchanger 120 is the same as heat exchanger 20, except that the orientation of heat exchanger 120 mirrors heat exchanger 20 about centerline C (such that first header 24 and third header 124 both connect to cool flow outlet 34 and second header 26 and fourth header 126 both connect to hot flow outlet 28). Heat exchanger pair 110 can be separate pieces fastened together, or heat exchanger pair 110 can be one continuous and monolithic piece. Heat exchanger pair 110 can be formed through a variety of manufacturing processes, such as forming pieces separately and fastening those pieces together or constructing all or parts of heat exchanger pair 110 through additive manufacturing. Heat exchanger pair 110 can be constructed from a variety of materials, including plastic, metal, an alloy, or another material. However, it may be beneficial to construct heat exchanger pair 110 from a thermally conductive material to promote the transfer of thermal energy from the hot fluid to the cool fluid. In one embodiment, the disclosed heat exchanger pair 110 is constructed from a nickel-based alloy. The flow of cool fluid through heat exchanger 20 and heat exchanger 120 can be the same (i.e., the same volume, flow rate, etc.) or different depending on the cooling needs and design considerations.

With heat exchanger 120 having fifth curved portion 162 (similar to first curve portion 62) and seventh curved portion 182 (similar to third curved portion 82), the second plurality of hot flow paths 200 through heat exchanger 120 are approximately the same length as the plurality of hot flow paths 100 through heat exchanger 20, resulting in approximately the same drop in pressure across all hot flow paths of heat exchanger pair 110. With heat exchanger 120 having sixth curved portion 172 (similar to second curved portion 72) and eighth curved portion 192 (similar to fourth curved portion 92), the second plurality of cool flow paths 202 through heat exchanger 120 are approximately the same length as the plurality of cool flow paths 102 through heat exchanger 20, resulting in approximately the same drop in pressure across all cool flow paths of heat exchanger pair 110.

Core 122 is adjacent to core 22 with the second plurality of hot flow channels 148 of core 122 flowing in the same direction as the plurality of hot flow channels 48 of core 22, and the second plurality of cool flow channels 150 of core 122 flowing in the same direction as the plurality of cool flow channels 50 of core 22. As shown in FIG. 3D, core 22 and core 122 can be integrated such that checkerboard pattern 52 and checkerboard pattern 152 are continuous with one another with no dividing characteristics between them, such as having the plurality of cool flow channels 50 of core 22 being adjacent to the second plurality of cool flow channels 150 of core 122. Rather, a portion of the plurality of hot flow channels 48 are adjacent to a portion of the second plurality of cool flow channels 150 in an alternating pattern, and a portion of the second plurality of hot flow channels 148 are adjacent to a portion of the plurality of hot flow channels 48 in an alternating pattern.

Third header 124 of heat exchanger 120 has the same configuration and functionality as first header 24 of heat exchanger 20, except that the orientation of third header 124 mirrors that of first header 24 about centerline C so that second cool flow outlet section 170 of third header 124 connects core 122 to cool flow outlet 34. As shown in FIG. 3B, in heat exchanger pair 110, both first cool flow outlet section 70 of first header 24 and second cool flow outlet section 170 of third header 124 connect to and convey cool fluid to cool flow outlet 34. With heat exchanger pair 110 providing cool fluid to cool flow outlet 34, cool flow outlet 34 can have a larger cross-sectional area (i.e., opening) than if only heat exchanger 20 was conveying cool fluid to cool flow outlet 34. Further, cool flow outlet 34 can have another configuration/shape, such as a rectangular shape, an oval shape, or another shape.

Third header 124 includes second hot flow inlet 128, which provides hot fluid that needs to be cooled by heat exchanger 120. As shown in FIG. 3B, second hot flow inlet 128 is on a side opposite that of hot flow inlet 28 of heat exchanger 20, but can have the same configuration as hot flow inlet 28. The hot fluid flowing into heat exchanger 120 from second hot flow inlet 128 can be the same hot fluid as that flowing into heat exchanger 20 from hot flow inlet 28, or the hot fluid can be a different hot fluid and/or from a different hot fluid source (i.e., a different medium from a different machine or different part of a machine in which heat exchanger pair 110 is located). However, the medium of hot fluid (whether the fluid is a gas or liquid and whether the fluid is the same gas or the same liquid) may need to be the same in both heat exchanger 20 and heat exchanger 120 if both are designed to flow into hot flow outlet 30.

As shown in FIG. 3C, first hot flow inlet section layers 68 of heat exchanger 20 and second hot flow inlet section layers 168 can be integrated to form continuous layers across the total cross section of heat exchanger pair 110, and first cool flow outlet section layers 78 of heat exchanger 20 and second cool flow outlet section layers 178 can also be integrated to form continuous layers across the total cross section of heat exchanger pair 110 (continuously across first header 24 and third header 124).

Fourth header 126 of heat exchanger 120 has the same configuration and functionality as second header 26 of heat exchanger 20, except that the orientation of fourth header 126 mirrors that of second header 26 about centerline C so that second hot flow outlet section 180 of fourth header 126 connects core 122 to hot flow outlet 30. In heat exchanger pair 110, both first hot flow outlet section 80 of second header 26 and second hot flow outlet section 180 of fourth header 126 connect to and convey hot fluid to hot fluid outlet 30. With heat exchanger pair 110 providing hot fluid to hot fluid outlet 30, hot fluid outlet 30 can have a larger cross-sectional area (i.e., opening) than if only heat exchanger 20 was conveying hot fluid to hot fluid outlet 30. Further, hot fluid outlet 30 can have another configuration/shape, such as a rectangular shape, an oval shape, or another shape.

Fourth header 126 includes second cool flow inlet 132, which provides cool fluid that is used to cool the hot fluid flowing through heat exchanger 120. As shown in FIG. 3F, second cool flow inlet 132 is on a side opposite that of cool flow inlet 32 of heat exchanger 20, but can have the same configuration as cool flow inlet 32. The cool fluid flowing into heat exchanger 120 from second cool flow inlet 132 can be the same cool fluid as that flowing into heat exchanger 20 from cool flow inlet 32, or the cool fluid can be a different cool fluid and/or from a different cool fluid source (i.e., a different medium from a different machine or different part of a machine in which heat exchanger pair 110 is located). However, the medium of cool fluid (whether the fluid is a gas or liquid and whether the fluid is the same gas or the same liquid) may need to be the same in both heat exchanger 20 and heat exchanger 120 if both are designed to flow into cool flow outlet 34.

As shown in FIG. 3E (and similar to FIG. 3C), first hot flow outlet section layers 88 of heat exchanger 20 and second hot flow outlet section layers 188 of heat exchanger 120 can be integrated to form continuous layers across the total cross section of heat exchanger pair 110, and first cool flow inlet section layers 98 of heat exchanger 20 and second cool flow inlet section layers 198 of heat exchanger 120 can also be integrated to form continuous layers across the total cross section of heat exchanger pair 110 (continuously across second header 26 and fourth header 126).

Heat exchanger 20 and heat exchanger 120 can be configured such that the hot fluid flowing through heat exchanger 20 is kept separate from and does not mix with the hot fluid flowing through heat exchanger 120. Similarly the cool fluid in heat exchanger 20 and the cool fluid in heat exchanger 120 can be kept separate. Heat exchanger pair 110 can be configured with two hot flow outlets and two cool flow outlets (one for each heat exchanger) and have a wall between heat exchanger 20 and heat exchanger 120. Further, heat exchanger pair 110 can be configured such that heat exchanger 20 and heat exchanger 120 share a hot flow inlet and a cool flow inlet while each having separate hot flow outlets and cool flow outlets (a configuration that is the inverse of that shown in FIGS. 3A-3F). Also, heat exchanger pair 110 can be incorporated into a larger heat exchanging system that includes more than two heat exchangers, as shown in FIG. 4.

FIG. 4 is a schematic of a heat exchanger system with four heat exchangers. Heat exchanger system 210 includes first heat exchanger 220, second heat exchanger 320, third heat exchanger 420, and fourth heat exchanger 520. First heat exchanger 220 is similar to heat exchanger 20 described previously, with first heat exchanger 220 having core 222, first header 224, and second header 226. Second heat exchanger 320 is similar to heat exchanger 120 described in regards to FIGS. 3A-3F, with second heat exchanger 320 having core 322, first header 324, and second header 326. Third heat exchanger 420 is similar to heat exchanger 20 described previously, with third heat exchanger 420 having core 422, first header 424, and second header 426. Fourth heat exchanger 520 is similar to heat exchanger 120 described in regards to FIGS. 3A-3F, with fourth heat exchanger 520 having core 522, first header 524, and second header 526.

On a first end, heat exchanger system 210 has first hot flow inlet 328 (providing hot fluid to first heat exchanger 220), second hot flow inlet 428 (providing hot fluid to second heat exchanger 320 and third heat exchanger 420), and third hot flow inlet 528 (providing hot fluid to fourth heat exchanger 520). Hot flow inlets 328, 428, and 528 provide hot fluid to heat exchanger system 210 in a similar configuration and functionality than those hot flow inlets described previously. Second hot flow inlet 428 can provide an equal amount of hot fluid to each of second heat exchanger 320 and third heat exchanger 420, or second hot flow inlet 428 can be configured to provide more hot fluid to one than the other. Similarly, on a second end, heat exchanger system 210 has first hot flow outlet 330 (providing an outlet for hot fluid from first heat exchanger 220 and second heat exchanger 320) and second hot flow outlet 430 (providing an outlet for hot fluid from third heat exchanger 420 and fourth heat exchanger 420).

On the second end, heat exchanger 210 has first cool flow inlet 332 (providing cool fluid to first heat exchanger 220), second cool flow inlet 432 (providing cool fluid to second heat exchanger 320 and third heat exchanger 420), and third cool flow inlet 532 (providing cool fluid to fourth heat exchanger 520). Cool flow inlets 332, 432, and 532 provide cool fluid to heat exchanger system 210 in a similar configuration and functionality than those cool flow inlets described previously. Second cool flow inlet 432 can provide an equal amount of cool fluid to each of second heat exchanger 320 and third heat exchanger 420, or second cool flow inlet 432 can be configured to provide more cool fluid to one than the other. Similarly, on the first end, heat exchanger system 210 has first cool flow outlet 334 (providing an outlet for cool fluid from first heat exchanger 220 and second heat exchanger 320) and second cool flow outlet 434 (providing an outlet for cool fluid from third heat exchanger 420 and fourth heat exchanger 420).

Cores 222, 322, 422, and 522 of heat exchanger system 210 can be discrete such that each does not interact with an adjacent core. Alternatively, cores 222, 322, 422, and 522 can be integrated such that a checkerboard pattern is continuous along an entire width of heat exchanger system 210 (similar to heat exchanger pair 110). Further, cores 222 and 322 can be integrated with one another and cores 422 and 522 can be integrated with one another, or cores 322 and 422 can be integrated with one another while cores 222 and 522 are discrete and do not interact with adjacent cores.

The flow paths through each heat exchanger 220, 320, 420, and 520 are similar to the flow paths through heat exchanger 20 and heat exchanger 120 described previously, with each of the flow paths having an approximately equal length. Further, the flow layers in first headers 224, 324, 424, and 524 can be integrated to form continuous layers across the total cross section of heat exchanger system 210 (continuously across first headers 224, 324, 424, and 524). Similarly, the flow layers in second headers 226, 326, 426, and 526 can be integrated to form continuous layers across the total cross section of heat exchanger system 210 (continuously across second headers 226, 326, 426, and 526).

As with heat exchanger pair 110, the hot flow paths through heat exchanger system 210 (whether the flow paths are through first heat exchanger 220, second heat exchanger 320, third heat exchanger 420, or fourth heat exchanger 52) are approximately equal in length because each heat exchanger includes a curved configuration (with multiple curved portions) similar to first curved portion 62, second curved portion 72, third curved portion 82, and fourth curved portion 92 of heat exchanger 20 (for first heat exchanger 220 and third heat exchanger 420) or fifth curved portion 162, sixth curved portion 172, seventh curved portion 182, and eighth curved portion 192 of heat exchanger 120 (for second heat exchanger 320 and fourth heat exchanger 520).

While heat exchanger system 210 is shown with four heat exchangers 220, 320, 420, and 520 in parallel, heat exchanger 210 can be configured to have any number of heat exchangers in parallel with additional heat exchangers similar to heat exchanger 20 and heat exchanger 120 described above being adjacent to either first heat exchanger 220 or fourth heat exchanger 520.

FIG. 5 is a schematic of another embodiment of a heat exchanger pair. Heat exchanger pair 610 is similar to heat exchanger pair 110 of FIGS. 3A-3F, except that heat exchanger pair 610 has first header 624 and second header 626 with first cool flow outlet section 670 and first cool flow inlet section 690 that do not have curves or a curved portion and allow cool fluid to flow in relatively straight cool flow paths of a plurality of cool flow paths 602 through heat exchanger pair 610. Heat exchanger pair 610 with straight cool flow paths of the plurality of cool flow paths 602 may be installed entirely within a cool flow duct or flow stream, limiting the need for a smaller, focused cool flow inlet and cool flow outlet. Instead, cool flow inlet 632 and cool flow outlet 634 span the entire width and height of heat exchanger pair 620 (i.e., cool flow inlet 632 and cool flow outlet 634 have the same or a larger cross-sectional area than core 622 of first heat exchanger 620 and core 122 of second heat exchanger 720).

Heat exchanger pair 610 includes first heat exchanger 620 having first hot flow inlet 628 adjacent first hot flow inlet section 660 with first curved portion 662, core 622, and hot flow outlet 630 adjacent first hot flow outlet section 680 with third curved portion 682 (similar to those components of heat exchanger 20 of heat exchanger pair 110 in FIGS. 3A-3F). Heat exchanger pair 610 also includes second heat exchanger 720 having second hot flow inlet 728 adjacent second hot flow inlet section 760 with fifth curved portion 762, core 722, and hot flow outlet 630 adjacent second hot flow outlet section 780 with seventh curved portion 782 (similar to those components of heat exchanger 120 of heat exchanger pair 110 in FIGS. 3A-3F). Core 622, core 722, first hot flow inlet 628, second hot flow inlet 728, hot flow outlet 630, first hot flow inlet section 660, first hot flow outlet section 680, second hot flow inlet section 760, and second hot flow outlet section 780 have the same configuration as that of heat exchanger pair 110 in FIGS. 3A-3F and convey hot fluid through heat exchanger pair 610 to cool the hot fluid.

As mentioned above, first cool flow outlet section 670 and first cool flow inlet section 690 do not have curved portions and allow cool fluid to flow in relatively straight cool flow paths of the plurality of cool flow paths 602 through heat exchanger pair 610. The cool fluid can be a gas or a liquid depending on the location and cooling requirements of heat exchanger pair 610. As with other embodiments, heat exchanger pair 610 can include multiple heat exchangers in series or parallel to one another.

Heat exchanger 20 (and other embodiments) having first header 24 and second header 26 includes core 22, which has a plurality of hot flow channels 48 and a plurality of cool flow channels 50. First header 24 and second header 26 have either a hot flow inlet section 60 with a cool flow outlet section 70 or a hot flow outlet section 80 with a cool flow inlet section 90. Heat exchanger 20 can include second header 26 (opposite first header 24) having either a hot flow outlet section 80 with a cool flow inlet section 90 or a hot flow inlet section 60 with a cool flow outlet section 70. Core 22 of heat exchanger 20 is configured to promote heat transfer between the hot fluid and the cool fluid by having the plurality of hot flow channels 48 and the plurality of cool flow channels 50 arranged in checkerboard pattern 52 with each of the plurality of hot flow channels 48 being surrounded by cooling flow channels 50. The plurality of hot flow channels 48 and the plurality of cool flow channels 50 can each have varying cross-sectional flow areas to promote heat transfer. First header 24 connects hot flow inlet 28 to core 22 and cool flow outlet 34 to core 22. Second header 26 connects cool flow inlet 32 to core 22 and hot flow outlet 30 to the core 22. Each header is arranged in an alternating hot-cool flow path orientation that transitions the flow from a singular channel inlet or outlet to checkerboard pattern 52 of core 22 so the change in temperature of the headers along a hot-cool flow path 100 and 102 is gradual, reducing thermal expansion issues that can be caused by a sudden increase (or decrease) in temperature along the plurality of flow paths 100 and 102. Further, first header 24 and second header 26 have curved portion 62, 72, 82, and 92 along each of the plurality of hot flow paths 100 and the plurality of cool flow paths 102, respectively, to make a length of flow equal along each of the plurality of hot flow paths 100 and the plurality of cool flow paths 102 so that the pressure drop across heat exchanger 20 is the same in all flow paths 100 and 102.

Other embodiments of the heat exchanger (heat exchanger pair 110 and heat exchanger system 210) can include multiple cores and multiple headers arranged in parallel with one hot flow inlet providing hot fluid to two different headers (that, in turn, provide hot fluid to two cores), with one cool flow inlet providing cool flow to two different headers, with one hot flow outlet connected to two different headers, and with one cool flow outlet connected to two different headers.

The heat exchanger disclosed herein has numerous benefits. Core 22 having checkerboard pattern 52 with varying cross-sectional flow areas can be arranged in a counter-flow configuration (i.e., the cool flow is in an opposite direction than the hot flow) that improves heat transfer across the entire length of heat exchanger 20, which increases the effectiveness of heat exchanger 20 for a given overall heat transfer area. The counter-flow configuration reduces the temperature differential across heat exchanger 20 because cool flow outlet 34 is aligned with hot flow inlet 28 in first header 24 (and vice versa in second header 26). Further, checkerboard pattern 52 increases the heat transfer surface area in heat exchanger 20, which increases the efficiency and limits the need to use fins or other projections into the plurality of hot flow paths 100 and the plurality of cool flow paths 102. Checkerboard pattern 52 enables optimization of high pressure channel shape (e.g., circular instead of rectangular) such that the stress from the pressure of the hot or cool fluid is minimized. The curved and alternating hot-cool flow orientation created by first header 24 and second header 26 gradually integrate the counter-flow hot and cool routes such that the increase in temperature of first header 24 and second header 26 is gradual, reducing thermal expansion issues and stresses that can result from a sudden increase (or decrease) in temperature along the plurality of hot flow paths 100 and the plurality of cool flow paths 102. The curved orientation of first header 24 and second header 26 balance out the flow length of each of the plurality of hot flow paths 100 and each of the plurality of cool flow paths 102 so that the pressure drop across heat exchanger 20 is constant along all flow paths.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments of the present invention.

A heat exchanger includes a first core with a first end and a second end having a first plurality of hot flow channels fluidly isolated from a first plurality of cool flow channels with the first plurality of hot flow channels and the first plurality of cool flow channels being arranged in a first checkerboard pattern. The heat exchanger also includes a first header connected to the first end of the first core. The first header includes a first hot flow inlet section and a first cool flow outlet section. The first hot inlet section is connected to the first plurality of hot flow channels and has a first curved portion with a first inner hot flow route that is longer than a first outer hot flow route. The first cool flow outlet section is connected to the first plurality of cool flow channels and is fluidly isolated from the hot flow inlet section.

The heat exchanger of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

The first cool flow outlet section of the first header includes a second curved portion with a first inner cool flow route that is longer than a first outer cool flow route.

The first cool flow outlet section of the first header includes a first straight flow portion having a first plurality of cool flow routes.

A second header connected to the second end of the first core that includes a first hot flow outlet section connected to the first plurality of hot flow channels with the first hot flow outlet section having a third curved portion with a second inner hot flow route that is longer than a second outer hot flow route, and a first cool flow inlet section connected to the first plurality of cool flow channels with the first cool flow inlet section being fluidly isolated from the first hot flow outlet section.

The first cool flow inlet section of the second header includes a fourth curved portion with a second inner cool flow route that is longer than a second outer cool flow route.

Each of the hot flow paths is configured so that a pressure drop of a fluid flowing through each of the hot flow paths is equal to one another.

The first cool flow inlet section of the second header includes a second straight flow portion having a second plurality of cool flow routes.

The first hot flow inlet section, the first plurality of hot flow channels, and the first hot flow outlet section form a plurality of hot flow paths between a hot flow inlet and a hot flow outlet with a length of each of the plurality of hot flow paths being substantially equal to one another.

The first hot flow outlet section of the second header is divided into first hot flow outlet section layers and the first cool flow outlet section of the second header is divided into first cool flow inlet section layers, wherein the first hot flow outlet section layers are each adjacent to a corresponding first cool flow inlet section layer within the second header.

The first hot flow inlet section has multiple first hot flow inlet section layers and the first cool flow outlet section has multiple first cool flow outlet section layers, wherein the first hot flow inlet section layers are each adjacent to a corresponding first cool flow outlet section layer.

A second core adjacent to the first core with the second core having a first end and a second end and a second plurality of hot flow channels fluidly isolated from a second plurality of cool flow channels and the second plurality of hot flow channels and the second plurality of cool flow channels being arranged in a second checkerboard pattern, and a third header connected to the first end of the second core with the first end of the second core being adjacent to the first end of the first core with the third header including a second hot flow inlet section adjacent to the first hot flow inlet section of the first header and the second hot flow inlet section connected to the second plurality of hot flow channels. The second hot flow inlet section also having a fifth curved portion with a third inner hot flow route that is longer than a third outer hot flow route with the third outer hot flow route being adjacent to the first outer hot flow route of the first header. The second header also including a second cool flow outlet section distant from the first cool flow outlet section of the first header, connected to the second plurality of cool flow channels, and being fluidly isolated from the second hot flow inlet section. The second cool flow outlet section also having a sixth curved portion with a third inner cool flow route that is longer than a third outer cool flow route with the third inner cool flow route being adjacent to the first inner cool flow route of the first header.

A first hot flow inlet with a first end connected to both of the first hot flow inlet section and the second hot flow inlet section.

A fourth header connected to the second end of the second core with the second end of the second core being adjacent to the second end of the first core. The fourth header includes a second hot flow outlet section distant from the first hot flow outlet section of the second header, connected to the second plurality of hot flow channels, and having a seventh curved portion with a fourth inner hot flow route that is longer than a fourth outer hot flow route with the fourth inner hot flow route being adjacent to the second inner hot flow route of the second header. The fourth header also includes a second cool flow inlet section adjacent to the first cool flow inlet section of the second header, connected to the second plurality of cool flow channels, being fluidly isolated from the second hot flow outlet section, and having an eighth curved portion with a fourth inner cool flow route that is longer than a fourth outer cool flow route with the fourth inner cool flow route being adjacent to the second inner cool flow route of the second header.

A first cool flow inlet with a first end connected to both the first cool flow inlet section and the second cool flow inlet section.

The first checkerboard pattern of the first core and the second checkerboard pattern of the second core are integrated with one another so that a hot flow channel of the first plurality of hot flow channels of the first core is adjacent to a cool flow channel of the second plurality of cool flow channels of the second core.

Another embodiment of a heat exchanger includes a core with hot flow channels and cool flow channels with the core having a center and outer edges and a first header connected to a first end of the core. The first header includes a hot flow inlet, first hot flow routes, two cool flow outlets distant from one another, and first cool flow routes. The first hot flow routes connect the hot flow channels to the hot flow inlet, with a first plurality of the first hot flow routes connecting the hot flow channels nearer the outer edges of the core to the hot flow inlet and being longer in length than a second plurality of the first hot flow routes that connect the hot flow channels nearer the center of the core to the hot flow inlet. The first cool flow routes connect the cool flow channels to one of the two cool flow outlets, with a first plurality of the first cool flow routes connecting the cool flow channels nearer the outer edges of the core to one of the two cool flow outlets and being shorter in length than a second plurality of the first cool flow routes that connect the cool flow channels nearer the center of the core to one of the two cool flow outlets.

The heat exchanger of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:

A second header connected to a second end of the core. The second header includes two hot flow outlets distant from one another, second hot flow routes connecting the hot flow channels to one of the two hot flow outlets with a first plurality of the second hot flow routes connecting the hot flow channels nearer the outer edges of the core to one of the two hot flow outlets and being shorter in length than a second plurality of the second hot flow routes that connect the hot flow channels nearer the center of the core to one of the two hot flow outlets, a cool flow inlet, and second cool flow routes connecting the cool flow channels to the cool flow inlet with a first plurality of the second cool flow routes connecting the cool flow channels nearer the outer edges of the core to the hot flow inlet and being longer in length than a second plurality of the second cool flow routes that connect the cool flow channels nearer the center of the core to the cool flow inlet.

The first hot flow routes, the hot flow channels, and the second hot flow routes form multiple hot flow paths between the hot flow inlet and the two hot flow outlets with a length of each of the multiple hot flow paths being substantially equal to one another.

The first cool flow routes, the cool flow channels, and the second cool flow routes form multiple cool flow paths between the two cool flow inlets and the cool flow outlet with a length of each of the multiple cool flow paths being substantially equal to one another.

Each of the first hot flow routes of the first header are adjacent to at least one of the first cool flow routes of the first header and each of the second hot flow routes of the second header are adjacent to at least one of the second cool flow routes of the second header.

Any relative terms or terms of degree used herein, such as “substantially,” “essentially,” “generally,” “approximately,” and the like should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations; incidental alignment variations; alignment or shape variations induced by thermal, rotational, or vibrational operational conditions; and the like.

While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. A heat exchanger comprising: a first core with a first end and a second end and having a first plurality of hot flow channels fluidly isolated from a first plurality of cool flow channels, the first plurality of hot flow channels and the first plurality of cool flow channels being arranged in a first checkerboard pattern; and a first header connected to the first end of the first core comprising: a first hot flow inlet section connected to the first plurality of hot flow channels, the first hot flow inlet section having a first curved portion with a first inner hot flow route that is longer than a first outer hot flow route; and a first cool flow outlet section connected to the first plurality of cool flow channels, the first cool flow outlet section being fluidly isolated from the first hot flow inlet section.
 2. The heat exchanger of claim 1, wherein the first cool flow outlet section of the first header includes a second curved portion with a first inner cool flow route that is longer than a first outer cool flow route.
 3. The heat exchanger of claim 1, wherein the first cool flow outlet section of the first header includes a first straight flow portion having a first plurality of cool flow routes.
 4. The heat exchanger of claim 1, further comprising: a second header connected to the second end of the first core comprising: a first hot flow outlet section connected to the first plurality of hot flow channels, the first hot flow outlet section having a third curved portion with a second inner hot flow route that is longer than a second outer hot flow route; and a first cool flow inlet section connected to the first plurality of cool flow channels, the first cool flow inlet section being fluidly isolated from the first hot flow outlet section.
 5. The heat exchanger of claim 4, wherein the first cool flow inlet section of the second header includes a fourth curved portion with a second inner cool flow route that is longer than a second outer cool flow route.
 6. The heat exchanger of claim 4, wherein the first cool flow inlet section of the second header includes a second straight flow portion having a second plurality of cool flow routes.
 7. The heat exchanger of claim 4, wherein the first hot flow inlet section, the first plurality of hot flow channels, and the first hot flow outlet section form a plurality of hot flow paths between a hot flow inlet and a hot flow outlet, a length of each of the plurality of hot flow paths being substantially equal to one another.
 8. The heat exchanger of claim 7, wherein each of the plurality of hot flow paths is configured so that a pressure drop of a fluid flowing through each of the plurality of hot flow paths is equal to one another.
 9. The heat exchanger of claim 4, wherein the first hot flow outlet section of the second header is divided into first hot flow outlet section layers and the first cool flow outlet section of the second header is divided into first cool flow inlet section layers, wherein the first hot flow outlet section layers are each adjacent to a corresponding first cool flow inlet section layer within the second header.
 10. The heat exchanger of claim 1, wherein the first hot flow inlet section has multiple first hot flow inlet section layers and the first cool flow outlet section has multiple first cool flow outlet section layers, wherein the first hot flow inlet section layers are each adjacent to a corresponding first cool flow outlet section layer.
 11. The heat exchanger of claim 1, further comprising: a second core adjacent to the first core, the second core having a first end and a second end and a second plurality of hot flow channels fluidly isolated from a second plurality of cool flow channels, the second plurality of hot flow channels and the second plurality of cool flow channels being arranged in a second checkerboard pattern; and a third header connected to the first end of the second core with the first end of the second core being adjacent to the first end of the first core, the third header comprising: a second hot flow inlet section adjacent to the first hot flow inlet section of the first header, the second hot flow inlet section connected to the second plurality of hot flow channels, the second hot flow inlet section having a fifth curved portion with a third inner hot flow route that is longer than a third outer hot flow route with the third outer hot flow route being adjacent to the first outer hot flow route of the first header; and a second cool flow outlet section distant from the first cool flow outlet section of the first header, the second cool flow outlet section connected to the second plurality of cool flow channels, the second cool flow outlet section being fluidly isolated from the second hot flow inlet section and having a sixth curved portion with a third inner cool flow route that is longer than a third outer cool flow route with the third inner cool flow route being adjacent to the first inner cool flow route of the first header.
 12. The heat exchanger of claim 11, further comprising: a first hot flow inlet with a first end connected to both of the first hot flow inlet section and the second hot flow inlet section.
 13. The heat exchanger of claim 11, further comprising: a fourth header connected to the second end of the second core with the second end of the second core being adjacent to the second end of the first core, the fourth header comprising: a second hot flow outlet section distant from the first hot flow outlet section of the second header, the second hot flow outlet section connected to the second plurality of hot flow channels, the second hot flow outlet section having a seventh curved portion with a fourth inner hot flow route that is longer than a fourth outer hot flow route with the fourth inner hot flow route being adjacent to the second inner hot flow route of the second header; and a second cool flow inlet section adjacent to the first cool flow inlet section of the second header, the second cool flow inlet connected to the second plurality of cool flow channels, the second cool flow inlet section being fluidly isolated from the second hot flow outlet section and having an eighth curved portion with a fourth inner cool flow route that is longer than a fourth outer cool flow route with the fourth inner cool flow route being adjacent to the second inner cool flow route of the second header.
 14. The heat exchanger of claim 12, further comprising: a first cool flow inlet with a first end connected to both the first cool flow inlet section and the second cool flow inlet section.
 15. The heat exchanger of claim 11, wherein the first checkerboard pattern of the first core and the second checkerboard pattern of the second core are integrated with one another so that a hot flow channel of the first plurality of hot flow channels of the first core is adjacent to a cool flow channel of the second plurality of cool flow channels of the second core.
 16. A heat exchanger comprising: a core with hot flow channels and cool flow channels, the core having a center and outer edges; and a first header connected to a first end of the core, the first header comprising: a hot flow inlet; first hot flow routes connecting the hot flow channels to the hot flow inlet, a first plurality of the first hot flow routes connecting the hot flow channels nearer the outer edges of the core to the hot flow inlet and being longer in length than a second plurality of the first hot flow routes that connect the hot flow channels nearer the center of the core to the hot flow inlet. two cool flow outlets; and first cool flow routes connecting the cool flow channels to one of the two cool flow outlets, a first plurality of the first cool flow routes connecting the cool flow channels nearer the outer edges of the core to one of the two cool flow outlets and being shorter in length than a second plurality of the first cool flow routes that connect the cool flow channels nearer the center of the core to one of the two cool flow outlets.
 17. The heat exchanger of claim 16, further comprising: a second header connected to a second end of the core, the second header comprising: two hot flow outlets distant from one another; second hot flow routes connecting the hot flow channels to one of the two hot flow outlets, a first plurality of the second hot flow routes connecting the hot flow channels nearer the outer edges of the core to one of the two hot flow outlets and being shorter in length than a second plurality of the second hot flow routes that connect the hot flow channels nearer the center of the core to one of the two hot flow outlets; a cool flow inlet; and second cool flow routes connecting the cool flow channels to the cool flow inlet, a first plurality of the second cool flow routes connecting the cool flow channels nearer the outer edges of the core to the hot flow inlet and being longer in length than a second plurality of the second cool flow routes that connect the cool flow channels nearer the center of the core to the cool flow inlet.
 18. The heat exchanger of claim 17, wherein the first hot flow routes, the hot flow channels, and the second hot flow routes form multiple hot flow paths between the hot flow inlet and the two hot flow outlets, a length of each of the multiple hot flow paths being substantially equal to one another.
 19. The heat exchanger of claim 16, wherein the first cool flow routes, the cool flow channels, and the second cool flow routes form multiple cool flow paths between the two cool flow inlets and the cool flow outlet, a length of each of the multiple cool flow paths being substantially equal to one another.
 20. The heat exchanger of claim 17, wherein each of the first hot flow routes of the first header are adjacent to at least one of the first cool flow routes of the first header and each of the second hot flow routes of the second header are adjacent to at least one of the second cool flow routes of the second header. 